I do not understand your question.
I do not see any problem in the log file. WinSCP seems to connect just fine.
Though in anyway, you should upgrade your copy of WinSCP, it's over 4 years old.

Hi.

We use WINSCP for sending AMEX file.

Now AMEX change the requirements and needs:
------------------
SSH Suite/Algorithm AMEX Requirement
Cipher Suite aes256-ctr
aes192-ctr
aes128-ctr
Message Authentication Code/MAC hmac-sha2-512
hmac-sha2-256
hmac-sha2-256-etm@openssh.com
hmac-sha2-512-etm@openssh.com
--------------------------

Cipher its compliant but HMAC NOT.

What are the changes in WINSCP settings?.


Actual settings:

Operating system windows2012R2.
Version: WinSCP_release_5.5.6 with script. Protocol SFTP.

Partial Log file:

---------------WINSCP log---------------------------------

. 2019-01-21 06:10:20.396 Looking up host "fsgateway.aexp.com"
. 2019-01-21 06:10:20.544 Connecting to 148.173.107.23 port 22
. 2019-01-21 06:10:20.791 Server version: SSH-2.0-Maverick_SSHD
. 2019-01-21 06:10:20.791 Using SSH protocol version 2
. 2019-01-21 06:10:20.791 We claim version: SSH-2.0-WinSCP_release_5.5.6
. 2019-01-21 06:10:20.912 Doing Diffie-Hellman group exchange
. 2019-01-21 06:10:21.281 Doing Diffie-Hellman key exchange with hash SHA-256
. 2019-01-21 06:10:22.369 Verifying host key rsa2 0x10001,0xd4b348e8acddbf1c 8b03d872727844f3 a7253876e00c618e c64e01877b519864 287767856f53e8ee b2dd06ddc19582de b39995606f9b6666 a0eabeaae7b2cbc5 8522b67795b15539 2f64cd2c685c3730 260583423a2accd4 29e41ac300c382b7 205066c27cb63428 4e687b727094f1b2 840790f870843f6f b2c5614d23c00bd2 8ca45c6594771b7d 8c9ac5a84aca52db d5ca60a8f259f050 9a0d6a05512a6fe2 c303544a67744e9a 4e6048343c078171 cef6f3352c92fa8a 324e2d0f03f5c979 09fb941d542eb1c7 01e08c5f453d7f01 bcbdcabb62dec95b 4a3cdf45ac7001b2 ed19989bf5745a9b ae3f9c39fda3cc4f 7d71a747f07b525e a6fc2e5991858b45 with fingerprint ssh-rsa 2048 c5:79:87:2f:37:49:2f:af:31:f5:24:a4:5d:99:0a:f9
. 2019-01-21 06:10:22.370 Host key matches cached key
. 2019-01-21 06:10:22.370 Host key fingerprint is:
. 2019-01-21 06:10:22.370 ssh-rsa 2048 c5:79:87:2f:37:49:2f:af:31:f5:24:a4:5d:99:0a:f9
. 2019-01-21 06:10:22.370 Initialised AES-256 SDCTR client->server encryption
. 2019-01-21 06:10:22.370 Initialised HMAC-SHA-256 client->server MAC algorithm
. 2019-01-21 06:10:22.370 Initialised AES-256 SDCTR server->client encryption
. 2019-01-21 06:10:22.371 Initialised HMAC-SHA-256 server->client MAC algorithm
! 2019-01-21 06:10:22.610 Using username "IE3625".
. 2019-01-21 06:10:22.731 Attempting keyboard-interactive authentication
. 2019-01-21 06:10:22.872 Prompt (6, SSH server: password, Using keyboard-interactive authentication.
. 2019-01-21 06:10:22.872 Enter password for IE3625, Password:)
. 2019-01-21 06:10:22.872 Using stored password.
. 2019-01-21 06:10:23.173 Access granted
. 2019-01-21 06:10:23.173 Opening session as main channel
. 2019-01-21 06:10:23.294 Opened main channel
. 2019-01-21 06:10:23.534 Started a shell/command

Thanks.